Cultured normal rat kidney (NRK) cells infected with a mutant avian sarcoma virus (ASV) which is temperature-sensitive for transformation will be used as a model system for investigating the relationship between reduced junctional communication and viral transformation. The rate and extent of junctional dye transfer between NRK cells will be assessed under conditions which permit or restrict cellular transformation. These studies will be repeated on other ASV-infected cell systems to indicate the general nature of the junctional response. Kinetic analyses will be performed to determine the rate at which junctional dye transfer characteristics are modified after infected cells are shifted to transformation-permissive temperatures. These data will be used to determine the relationship, if any, between impaired junctional dye transfer and cell surface phenomenon associated with viral transformation (membrane ruffling and retraction). The latter will be monitored by scanning electron microscopy and time lapse cinematography following shifts to permissive temperatures. Since the src gene product may contain protein kinase activity, initial studies will be conducted to determine if pp60 src acts directly on membrane components via phosphorylation of membrane proteins. Protein phosphorylation of membrane components will be measured with radiolabeled phosphate under transformation-permissive or restrictive conditions.